Method for producing dinuclear transition metal complexes as olefin polymerization catalyst

ABSTRACT

The object of the present invention is to provide a method for producing a dinuclear transition metal complex of formula (1) by reacting cyclopentadienyl ligand compound of formula (2) and substituted transition metal of formula (3).  
     Cp-Si(R) 2 HNANHSi(R) 2 -Cp  (Formula  2 )  
     wherein,  
     A represents C 2-30  alkylene, substituted alkylene, arylene, substituted arylene, cycloalkylene, substituted cycloalkylene, biarylene or substituted biarylene;  
     Cp represents a ligand compound having cyclopentadienyl skeleton selected from the group consisting of cyclopentadienyl, substituted cyclopentadienyl, indenyl, substituted indenyl, fluorenyl and substituted fluorenyl;  
     R represents C 1-20  alkyl or substituted alkyl;  
     H represents hydrogen atom;  
     Si represents silicon atom; and  
     N represents nitrogen atom.  
     M(NR 2 ′) 4   (Formula  3 )  
     M represents transition metal of Periodic Table IV selected from titanium, zirconium and hafnium;  
     R′ represents C 1-6  alkyl.  
                 
 
     wherein,  
     X represents halogen atom or alkylamine; and  
     A, R, Si, N, Cp and M are same as defined above.

BACKGROUND OF THE INVENTION

[0001] The present invention relates to a method for producing adinuclear transition metal complex as olefin polymerization catalyst.More particularly, the present invention a method for producing adinuclear transition metal complex of formula (1) by reactingcyclopentadienyl ligand compound of formula (2) and substitutedtransition metal of formula (3).

Cp-Si(R)₂HNANHSi(R)₂-Cp  (Formula 2)

[0002] wherein,

[0003] A represents C₂₋₃₀ alkylene, substituted alkylene, arylene,substituted arylene, cycloalkylene, substituted cycloalkylene, biaryleneor substituted biarylene;

[0004] Cp represents a ligand compound having cyclopentadienyl skeletonselected from the group consisting of cyclopentadienyl, substitutedcyclopentadienyl, indenyl, substituted indenyl, fluorenyl andsubstituted fluorenyl;

[0005] R represents C₁₋₂₀ alkyl or substituted alkyl;

[0006] H represents hydrogen atom;

[0007] Si represents silicon atom; and

[0008] N represents nitrogen atom.

M(NR₂′)₄  (Formula 3)

[0009] M represents transition metal of Periodic Table 1V selected fromtitanium, zirconium and hafnium;

[0010] R′ represents C₁₋₆ alkyl.

[0011] wherein,

[0012] X represents halogen atom or alkylamine; and

[0013] A, R, Si, N, Cp and M are same as defined above.

[0014] Metallocene catalyst using transition metal of Periodic Table IVhas been used as an effective catalyst for various organic catalystreactions and polymerization reactions for olefin polymer. Further, saidmetallocene catalyst has many merits of excellent catalytic activity andconvenience for controlling molecular weight and molecular weightdispersion compared to conventional Ziegler-Natta catalyst. Amongtransition metal compounds of Periodic Table IV, the catalyst havingcyclopentadienyl skeleton has an excellent catalytic activity and U.S.Pat. Nos. 4,584,346 and 5,965,785 disclosed that constrained geometrycatalyst (CGC) having the structure of cyclopentadienyl connected withalkyl or aryl amine shows the excellent catalytic activity.

[0015] To obtain said metallocene, following process has been used. (i)Dianion is obtained by reaction of ligand and 2 mole of alkyl lithiumusing THF or ethyl ether as a solvent; (ii) Ligand of lithium salt isreacted with TiCl₄(THF)₂, TiCl₄(Et₂O)₂ or ZrCl₄ at extremely lowtemperature (−78° C.); (iii) The obtained product is purified andrecrystallized after removing by-product, such as, LiCl. However, suchprocess is hard to apply to the industry, because of the using solventand the extremely low temperature.

[0016] Among various metallocene, a dinuclear transition metal complexin which two metals are contained in one compound has been developed. InKorea Polymer Journal, Vol. 9, No.2, pp 71-83(2001), th synthesis ofdinuclear transition metal complex and its polymerization method havebeen disclosed. Such dinuclear transition metal complex has an excellentolefin polymerization activity, especially, the polymerization ofethylene/styrene.

[0017] In WO 00/02891, the synthesis of dinuclear transition metalcomplex having two cyclopentadienyl ligand is disclosed. However, saiddinuclear transition metal complex also can be obtained in similarsynthetic process of CGC. In detail, (i) Tetra-anion ligand is obtainedby reaction of dinuclear ligand and 4 mole of alkyl lithium using THF orethyl ether as a solvent; (ii) Dinuclear ligand of lithium salt isreacted with 2 mole of TiCl₄(THF)₂, TiCl₄(Et₂O)₂ or ZrCl₄ at extremelylow temperature (−78° C.); (iii) The obtained product is purified andrecrystallized after removing by-product, such as, LiCl. Further, incase of dinuclear metallocene, it is hard to purify or crystallize themetallocene, since two kinds of reaction compound are obtained.Therefore, according to the method in WO 00/02891, dinuclear metalloceneis obtained in less than 3% yield, because dinuclear ligand having twocyclopentadienyl is used.

[0018] To overcome said drawbacks, the present invention has developed aconvenient method for producing dinuclear metallocene in anindustrialization scale, which also affords the high yield for preparingdinuclear metallocene by removing the hard steps of metallocenesynthesis

SUMMARY OF THE INVENTION

[0019] The object of the present invention is to provide a method forproducing a dinuclear transition metal complex of formula (1) byreacting cyclopentadienyl ligand compound of formula (2) and substitutedtransition metal of formula (3).

Cp-Si(R)₂HNANHSi(R)₂-Cp  (Formula 2)

[0020] wherein,

[0021] A represents C₂₋₃₀ alkylene, substituted alkylene, arylene,substituted arylene, cycloalkylene, substituted cycloalkylene, biaryleneor substituted biarylene;

[0022] Cp represents a ligand compound having cyclopentadienyl skeletonselected from the group consisting of cyclopentadienyl, substitutedcyclopentadienyl, indenyl, substituted indenyl, fluorenyl andsubstituted fluorenyl;

[0023] R represents C₁₋₂₀ alkyl or substituted alkyl;

[0024] H represents hydrogen atom;

[0025] Si represents silicon atom; and

[0026] N represents nitrogen atom.

M(NR₂′)₄  (Formula 3)

[0027] M represents transition metal of Periodic Table IV selected fromtitanium, zirconium and hafnium;

[0028] R′ represents C₁₋₆ alkyl.

[0029] wherein,

[0030] X represents halogen atom or alkylamine; and

[0031] A, R, Si, N, Cp and M are same as defined above.

[0032] As a reaction solvent, toluene, xylene or monochlorobenzene canbe used.

[0033] Further, the reaction is carried out on 20˜120° C., preferably,100˜120° C.

[0034] Said substituted transition metal is one or more selected fromthe group consisting of Ti(NR₂)₄, Zr(NR₂)₄ Hf(NR₂)₄ (R is C₁₋₆ alkyl).

DETAILED DESCRIPTION OF THE INVENTION

[0035] In conventional method for producing metallocene compound,tetrahydrofuran (THF) or diethylether (Et₂O) has been used as a reactionsolvent. Further, the extremely low temperature (−78˜40° C.) has to bemaintained in order to react the ligand and transition metal. Tomaintain such extremely low temperature, highly expensive apparatus andcooling agent should be required.

[0036] On the other hand, the reactant, tetra-anion ligand has to bemade after reacting dinuclear ligand and 4 mole of alkyl lithium in thepresence of THF or diethylether for reacting transition metal. However,such tetra-anion ligand is very unstable in the presence of air ormoisture as well as the risk of burning. Further, to obtain thedinuclear metallocene, the filtration of LiCl is required. Therefore,the yield of dinuclear metallocene has been very low.

[0037] To overcome such drawbacks in conventional method, the presentinvention has been accomplished.

[0038] (1) The present invention has developed the reaction solvent.Therefore, various aromatic solvent can be used in the presentinvention. As a preferred reaction solvent, toluene or xylene can beused.

[0039] (2) Instead of metal compound required for extremely low reactiontemperature, such as ZrCl₄, HfCl₄, TiCl₄(THF)₂ or TiCl₄(Et₂O)₂, the mildmetal compound of Ti(NR₂)₄, Zr(NR₂)₄ or Hf(NR₂)₄ (R is C₁₋₆ alkyl) canbe used to proceed with the reaction at higher than room temperature,20˜120° C., preferably, 100˜120° C.

[0040] (3) Using Ti(NR₂)₄, Zr(NR₂)₄ or Hf(NR₂)₄, tetra-anion ligandunstable to air or moisture is not required as a intermediate.Therefore, it is applied to industrialized scale. Further, withoutformation of LiCl, unnecessary filtraion process can be reduced.

[0041] (4) The reaction between dinuclear ligand and Ti(NR₂)₄, Zr(NR₂)₄or Hf(NR₂)₄ can be performed in quantitative level. Therefore, thepurification and recrystallization to obtain metallocene can be improvedand the yield of metallocene also increases.

[0042] After Ti(NR₂)₄, Zr(NR₂)₄ or Hf(NR₂)₄ is reacted with the compoundof formula (2) purging nitrogen gas, the compound of formula (1) iseasily obtained by removing reaction byproduct, dimethylamine. At thistime, the obtained compound of formula (1) has C₁₋₆ alkyl radical as X.Also, the compound of formula (1) has halide as X if trimethylsilylchloride is added.

[0043] The present invention can be explained more concretly byfollowing examples. However, the scope of the present invention shallnot be limited by following examples.

EXAMPLE I

[0044] Preparation of Compound of Formula (2)

[0045] Magnetic bar is laid on the 100 ml of branched round flask andnitrogen gas is purged. 1 g of 4-phenylenediamine and 50 ml oftetrahydrofuran are added as stirred and keep the temperature at 0° C.Then, 10 ml of normal buthyl lithium (2.0 mole) is added slowly andraise the temperature to the room temperature and the mixture is stirredfor 1 hour. Then, 4.6 g of tetramethylcyclopentadienylsilylchloride (Me₄CpSiMe₂Cl) dissolved with THF is added drop by drop slowly. Afteradding, the mixture is stirred for 12 hours at room temperature and thesolvent is removed under reduced pressure. Then, brown color solid isobtained. After dissolving solid with 100 ml of hexane, LiCl is removedusing filter. Filtered solution is concentrated to 30 ml and laid onrefrigerator. Then, white crystalline solid is obtained and it is washedwith hexane and dried under reduced pressure. Finally, 3.1 g of thecompound (m-[(Me₄C₅H₅)Si(Me)₂(NH)]₂C₆H₄) is obtained (yield 67%).

[0046]¹H NMR (CDCl₃, 400 MHz) δ 6.50 (s, 4H), 3.15 (s, 2H), 2.98 (s,2H), 1.93 (s, 12H), 1.82 (s, 12H), 1.13 (s, 12H).

EXAMPLE II

[0047] Preparation of Compound of Formula (1) (X=Alkyl)

[0048] Magnetic bar is laid on the 25 ml of branched round flask andnitrogen gas is purged. 465 mg of m-[(Me₄C₅H₅)Si(Me)₂(NH)]₂C₆H₄ (1 mM)and 537 mg of Zr(NMe₂)₄ (2 mM) and 5 ml of toluene are added and heatedto 100° C. Maintaining 100° C. for about 12 hours, the mixture isstirred under nitrogen atmosphere and cooled to the room temperature.After filtration, 840 mg of brown color solidm-[Me₂Zr(Me₄C₅H₄)Si(Me)₂(N)]₂C₆H₄ is obtained (yield 99%).

[0049]¹H NMR (CDCl₃, 400 MHz) δ 6.58 (s, 4H), 2.80 (s, 24H), 2.19 (s,12H), 2.10 (s, 12H), 0.61 (s, 12H).

EXAMPLE III

[0050] Preparation of Compound of Formula (1) (X=Halide)

[0051] Magnetic bar is laid on the 25 ml of branched round flask andnitrogen gas is purged. 465 mg of m-[(Me₄C₅H₅)Si(Me)₂(NH)]₂C₆H₄ (1 mM)and 537 mg of Zr(NMe₂)₄ (2 mM) and 5 ml of toluene are added and heatedto 100° C. Maintaining 100° C. for about 12 hours, the mixture isstirred under nitrogen atmosphere and cooled to the room temperature.Then, 0.7 ml of trimethylsilylchloride (Me₃SiCl) (5 mM) is added. Afterheating the solution up to 60° C., the mixture is stirred for 1 hour andsolid is obtained. After filtering the solid and washing with hexane,650 mg of brown color of solid m-[Cl₂Zr(Me₄C₅H₄)Si(Me)₂(N)]₂C₆H₄ isfinally obtained under reduced pressure (yield 80.1%).

COMPARATIVE EXAMPLE

[0052] Magnetic bar is laid on the 500 ml of branched round flask andnitrogen gas is purged. 1 mg of m-[(Me₄C₅H₅)Si(Me)₂(NH)]₂C₆H₄ (0.025M)and 150 ml of diethylether are added and stirred to keep −78° C. Then,71 ml of methyllithium (1.4M) is added and heated to the roomtemperature and stirred for 3 hours. 8.4 g of solidm-[(Me₄C₅H₅Li)Si(Me)₂(NLi)]₂C₆H₄ is obtained after filtering white solidand drying under reduced pressure (70.4%). Then, 4.2 g ofm-[(Me₄C₅H₅)Si(Me)₂(NH)]₂C₆H₄ (0.0088M) is added to 200 ml ofdiethylether and stirred. After keeping −78° C., 5.81 g of TiCl₄(Et₂O)₂(0.0172M) is added and heated to the room temperature and stirred for 12hours. After removing the solvent under reduced pressure, the mixture isdissolved with 100 ml of pentane and filtered to remove byproduct LiCl.Filtered solution is concentrated to 30 ml and laid on refrigerator.Obtained yellow solid is filtered and washed with pentane and driedunder reduced pressure. Finally, 0.45 g ofm-[Cl₂Ti(Me₄C₅H₄)Si(Me)₂(N)]₂C₆H₄ is obtained (yield 7.3%).

EXAMPLE IV

[0053] Comparison of Preparation Yield of Catalyst

[0054] The preparation yield of catalyst from same starting materialm-[(Me₄C₅H₅)Si(Me)₂(NH)]₂C₆H₄ according to the method of example 1 andcomparative example is measured and described as following table. TABLEI Comparison of preparation yield of catalyst yield (X = halide) ExampleI 80.1% Com. Ex. I  2.6%

EXAMPLE V

[0055] Polymerization of Ethylene

[0056] Ethylene polymerization is carried out using toluene solvent in100 ml of reactor under present atmosphere. 45 ml of toluene is added tothe reactor and keep the temperature at 60° C. 4 ml of methylaluminoxene (11.32 mM) of cocatalyst is added and stirred for 5 minutesand m-[Cl₂Zr(Me₄C₅H₄)Si(Me)₂(N)]₂C₆H₄ solution (18.5 μmmol) of catalystis added. Then, ethylene is injected for 1 hour. After 1 hour, theinjection of ethylene is finished and mixture is poured to 200 ml ofMeOH/HCl solution to stop the reaction. After drying white solid, 240 gof polyethylene (activity 13 kg mol⁻¹ h⁻¹ bar⁻¹) is obtained.

[0057] The advantageous effect of the present invention can be describedas follows;

[0058] i) The mild of reaction temperature; ii) Without formation oftetra-anion ligand; iii) Without formation of byproduct such aslithiumchloride.

[0059] Therefore, the method of present invention can afford a dinuclearmetallocene catalyst in an excellent yield and convenient process.

What is claimed is:
 1. A method for producing a dinuclear transitionmetal complex of formula (1) by reacting cyclopentadienyl ligandcompound of formula (2) and substituted transition metal of formula (3).Cp-Si(R)₂HNANHSi(R)₂-Cp  (Formula 2) wherein, A represents C₂₋₃₀alkylene, substituted alkylene, arylene, substituted arylene,cycloalkylene, substituted cycloalkylene, biarylene or substitutedbiarylene; Cp represents a ligand compound having cyclopentadienylskeleton selected from the group consisting of cyclopentadienyl,substituted cyclopentadienyl, indenyl, substituted indenyl, fluorenyland substituted fluorenyl; R represents C₁₋₂₀ alkyl or substitutedalkyl; H represents hydrogen atom; Si represents silicon atom; and Nrepresents nitrogen atom. M(NR₂′)₄  (Formula 3) M represents transitionmetal of Periodic Table IV selected from titanium, zirconium andhafnium; R′ represents C₁₋₆ alkyl.

wherein, X represents halogen atom or alkylamine; and A, R, Si, N, Cpand M are same as defined above.
 2. A method for producing a dinucleartransition metal complex of formula (1) according to claim 1, whereinsaid reaction solvent is toluene, xylene or monochlorobenzene.
 3. Amethod for producing a dinuclear transition metal complex of formula (1)according to claim 1, wherein the reaction is carried out on 20˜120° C.,preferably, 100˜120° C.
 4. A method for producing a dinuclear transitionmetal complex of formula (1) according to claim 1, wherein saidsubstituted transition metal is one or more selected from the groupconsisting of Ti(NR₂)₄, Zr(NR₂)₄, Hf(NR₂)₄ (R is C₁₋₆ alkyl).